Elastic wave filter apparatus

ABSTRACT

An elastic wave filter apparatus includes at least one excitation electrode, a first electrode land, and second electrode lands provided on a first main surface of a device substrate including a piezoelectric layer. A signal terminal and metal members are provided on a second main surface of the device substrate. The first electrode land and the signal terminal are connected to a signal potential, and the second electrode lands and the metal members are connected to a ground potential. A first connection electrode connects the first electrode land and the signal terminal, and a second connection electrode connects at least one of the second electrode lands and at least one of the metal members. The at least one metal member connected to the second connection electrode overlaps at least a portion of the at least one excitation electrode across the device substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2015-126802 filed on Jun. 24, 2015 and is a ContinuationApplication of PCT Application No. PCT/JP2016/063990 filed on May 11,2016. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an elastic wave filter apparatusincluding an elastic wave filter device and a mounting substrate onwhich an elastic wave filter device is mounted.

2. Description of the Related Art

In an elastic wave filter apparatus described in Japanese UnexaminedPatent Application Publication No. 2009-159195, an IDT electrode and awiring electrode connected to the IDT electrode are provided on apiezoelectric substrate. A frame member made of a metal frame isprovided around a portion where the IDT electrode and the wiringelectrode are provided. A covering member is provided so as to cover theopening of the frame member. Accordingly, a hollow space in which theIDT electrode and the wiring electrode are located is formed. Aplurality of through electrodes are provided in the piezoelectricsubstrate. A first end of each through electrode is electricallyconnected to the wiring electrode. A second end of each throughelectrode is electrically connected to a terminal electrode provided ona bottom surface of the piezoelectric substrate.

When in use, the above-described elastic wave filter apparatus ismounted on the mounting substrate from the terminal electrode side. Heatis generated at the IDT electrode in the elastic wave filter apparatuswhen the IDT electrode is driven. This heat goes through theabove-mentioned wiring electrode and through electrodes and reaches theterminal electrode. Thus, some of the heat is dissipated by the terminalelectrode. However, heat dissipation is not sufficient.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide elastic wavefilter apparatuses with excellent heat dissipation.

An elastic wave filter apparatus according to a preferred embodiment ofthe present invention includes a device substrate including apiezoelectric layer, the device substrate including a first main surfaceand a second main surface that face each other; at least one excitationelectrode provided on the first main surface of the device substrate,the at least one excitation electrode defining an elastic wave filterdevice; a first electrode land and a plurality of second electrode landsprovided on the first main surface of the device substrate and connectedto the at least one excitation electrode, the first electrode land beingconnected to a signal potential, the plurality of second electrode landsbeing connected to a ground potential; a signal terminal and a pluralityof metal members provided on the second main surface of the devicesubstrate, the signal terminal being connected to the signal potential,the plurality of metal members being connected to the ground potential;a first connection electrode that connects the first electrode land andthe signal terminal; and a second connection electrode that connects atleast one of the plurality of second electrode lands and at least one ofthe plurality of metal members. The at least one of the plurality ofmetal members connected to the second connection electrode overlaps atleast a portion of the at least one excitation electrode across thedevice substrate.

Another preferred embodiment of an elastic wave filter apparatusaccording to the present invention includes a supporting layer providedon the first main surface of the device substrate, a cover provided onthe supporting layer, and the supporting layer, the cover, and the firstmain surface of the piezoelectric substrate define a hollow portion inwhich the excitation electrode is located.

In a preferred embodiment of an elastic wave filter apparatus accordingto the present invention, at least one of the plurality of metal membersis preferably a ground terminal.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, an area of at least one of theplurality of metal members is preferably greater than an area of thesignal terminal.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the first and second connectionelectrodes preferably penetrate through the device substrate. In thiscase, the elastic wave filter apparatus is able to be made smaller.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the device substrate preferablyincludes a lateral surface connecting the first main surface and thesecond main surface, and the first and second connection electrodes areprovided on the lateral surface.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the first and second connectionelectrodes and the at least one of the plurality of metal memberspreferably include a plating film. In this case, the first and secondconnection electrodes and the at least one of the plurality of metalmembers are able to be easily formed by plating.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the signal terminal preferablyincludes a plurality of signal terminals provided on the second mainsurface of the device substrate, at least one of the plurality of signalterminals is located on one of two sides of the at least one of theplurality of metal members connected to the second connection electrode,and at least another one of the plurality of signal terminals is locatedon the other side of the at least one of the plurality of metal membersconnected to the second connection electrode In this case, isolationbetween signal terminals is increased. Therefore, the attenuationcharacteristics are less likely to deteriorate.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the plurality of signal terminalspreferably have a rectangular or substantially rectangular planar shape.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the plurality of signal terminalspreferably have a semicircular or substantially semicircular planarshape.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, each of the plurality of signalterminals preferably extends along one of opposed edges of the devicesubstrate.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the device substrate is preferably apiezoelectric substrate including the piezoelectric layer.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the device substrate preferablyincludes a supporting substrate and the piezoelectric layer provided onthe supporting substrate.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, at least one of the plurality ofmetal members is preferably located on one of two sides of the at leastone of the plurality of metal members connected to the second connectionelectrode, and at least another one of the plurality of metal members ispreferably located on the other side of the at least one of theplurality of metal members connected to the second connection electrode.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the plurality of metal memberspreferably have a rectangular or substantially rectangular planar shape.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, the plurality of metal memberspreferably have a semicircular or substantially semicircular planarshape.

In another preferred embodiment of an elastic wave filter apparatusaccording to the present invention, each of the plurality of metalmembers preferably extends along one of opposed edges of the devicesubstrate.

According to various preferred embodiments of the present invention,elastic wave filter apparatuses with excellent heat dissipation.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially-notched front cross-sectional view illustrating aportion where an elastic wave filter apparatus according to a firstpreferred embodiment of the present invention is mounted on a mountingsubstrate.

FIG. 2 is a front cross-sectional view of the elastic wave filterapparatus according to the first preferred embodiment of the presentinvention.

FIG. 3 is a bottom view of the elastic wave filter apparatus accordingto the first preferred embodiment of the present invention.

FIG. 4 is a graph illustrating the attenuation amount frequencycharacteristics of a transmission filter of a duplexer serving as anexample of the first preferred embodiment of the present invention, andthe attenuation amount frequency characteristics of a transmissionfilter of a duplexer of a comparative example.

FIG. 5 is a graph illustrating the attenuation amount frequencycharacteristics of a reception filter of the duplexer serving as anexample of the first preferred embodiment of the present invention, andthe attenuation amount frequency characteristics of a reception filterof the duplexer of a comparative example.

FIG. 6 is a graph illustrating the isolation characteristics of thetransmission filter of the duplexer serving as an example of the firstpreferred embodiment of the present invention, and the isolationcharacteristics of the transmission filter of the duplexer of acomparative example.

FIG. 7 is a bottom view of an elastic wave filter apparatus according toa second preferred embodiment of the present invention.

FIG. 8 is a bottom view of an elastic wave filter apparatus according toa third preferred embodiment of the present invention.

FIG. 9 is a graph illustrating a heat simulation result in the case ofchanging the thickness of a piezoelectric substrate to about 50 μm,about 80 μm, or about 125 μm in the elastic wave filter apparatusaccording to the third preferred embodiment of the present invention,and the case of applying electric power to an IDT electrode 3 (aplurality of IDTs of the transmission filter).

FIG. 10 is a front cross-sectional view of an elastic wave filterapparatus according to a fourth preferred embodiment of the presentinvention.

FIG. 11 is a bottom view of an elastic wave filter apparatus accordingto a fifth preferred embodiment of the present invention.

FIG. 12 is a bottom view of an elastic wave filter apparatus accordingto a sixth preferred embodiment of the present invention.

FIG. 13 is a bottom view of an elastic wave filter apparatus accordingto a seventh preferred embodiment of the present invention.

FIG. 14 is a bottom view of an elastic wave filter apparatus accordingto an eighth preferred embodiment of the present invention.

FIG. 15 is a front cross-sectional view of an elastic wave filterapparatus according to a ninth preferred embodiment of the presentinvention.

FIG. 16 is a bottom view of an elastic wave filter apparatus accordingto a tenth preferred embodiment of the present invention.

FIG. 17 is a bottom view of an elastic wave filter apparatus accordingto an eleventh preferred embodiment of the present invention.

FIG. 18 is a front cross-sectional view of an elastic wave filterapparatus according to a twelfth preferred embodiment of the presentinvention.

FIG. 19 is a front cross-sectional view of an elastic wave filterapparatus according to a thirteenth preferred embodiment of the presentinvention.

FIG. 20 is a partially-notched front cross-sectional view illustrating aportion where an elastic wave filter apparatus according to a fourteenthpreferred embodiment of the present invention is mounted on a mountingsubstrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the drawings.

Note that the preferred embodiments described in the specification areillustrative, and it is to be noted that a partial replacement orcombination of elements or features is possible between differentpreferred embodiments.

FIG. 1 is a partially-notched front cross-sectional view illustrating astructure where an elastic wave filter apparatus according to a firstpreferred embodiment of the present invention is mounted on a mountingsubstrate. FIG. 2 is a front cross-sectional view of the elastic wavefilter apparatus according to the first preferred embodiment. FIG. 3 isa bottom view of the elastic wave filter apparatus according to thefirst preferred embodiment.

An elastic wave apparatus 1 according to the present preferredembodiment preferably is a duplexer, for example. As illustrated in FIG.2 , the elastic wave filter apparatus 1 includes a piezoelectricsubstrate 2 which defines a device substrate. That is, the devicesubstrate is preferably the piezoelectric substrate including onepiezoelectric layer in the present preferred embodiment. Thepiezoelectric substrate 2 is made of an appropriate piezoelectricmaterial, such as piezoelectric single crystal or piezoelectricceramics. Preferably, LiTaO₃ or LiNbO₃ may be used as the piezoelectricsingle crystal.

An IDT electrode 3 and an IDT electrode 4 are provided on thepiezoelectric substrate 2. The IDT electrode 3 defines a portion of anelastic wave resonator. The elastic wave resonator is preferably oneelastic wave resonator of a transmission filter of the duplexer. Thetransmission filter includes a plurality of elastic wave resonators.

The IDT electrode 4 is preferably an electrode of a reception filter.The reception filter includes a longitudinally coupled resonator-typeelastic wave filter.

In addition to the IDT electrodes 3 and 4, a first electrode land 5 aand a second electrode land 6 a are provided on a first main surface 2 aof the piezoelectric substrate 2. The first electrode land 5 a iselectrically connected to the IDT electrode 3. The second electrode land6 a is electrically connected to the IDT electrode 4. The firstelectrode land 5 a is an electrode land connected to a signal potential,and the second electrode land 6 a is an electrode land connected to aground potential.

Another second electrode land 6 b is provided in an area between the IDTelectrode 3 and the IDT electrode 4. The second electrode land 6 b iselectrically connected to the IDT electrodes 3 and 4.

Signal terminals 7 a to 7 c and ground terminals 8 a to 8 e are providedon a second main surface 2 b of the piezoelectric substrate 2. Thesignal terminals 7 a to 7 c and the ground terminals 8 a to 8 e areportions connected to the signal potential and the ground potential,respectively, outside the elastic wave filter apparatus 1.

A heat diffusion layer 9 is provided on the second main surface 2 b. Theheat diffusion layer 9 is made of a material whose thermal conductivityis higher than the piezoelectric material configuring the piezoelectricsubstrate 2. Metal, or various insulators or semiconductors with higherthermal conductivity than the piezoelectric substrate 2 may be used assuch a material. Preferably, the heat diffusion layer 9 is made of metalbecause it has high thermal conductivity and has electricalconductivity. Examples of such metal include Al, Cu, Ag, Au, Ti, Ni, Sn,Pd, Cr, and NiCr. Alternatively, a plurality of metal films made of suchmetals may be laminated. A portion of the heat diffusion layer 9overlaps at least a portion of the IDT electrodes 3 and 4 across thepiezoelectric substrate.

The signal terminal 7 a faces the first electrode land 5 a across thepiezoelectric substrate 2. The ground terminal 8 a faces the secondelectrode land 6 a across the piezoelectric substrate 2.

At the same time, the second electrode land 6 b is located at a positionthat overlaps the heat diffusion layer 9 across the piezoelectricsubstrate 2.

A first connection electrode 10 penetrates through the piezoelectricsubstrate 2. The first connection electrode 10 electrically connects thefirst electrode land 5 a and the signal terminal 7 a. Likewise, a secondconnection electrode 11 penetrates through the piezoelectric substrate2. The second connection electrode 11 electrically connects the secondelectrode land 6 a and the ground terminal 8 a.

Furthermore, another second connection electrode 12 penetrates throughthe piezoelectric substrate 2. The second connection electrode 12connects the second electrode land 6 b and the heat diffusion layer 9.

The first and second connection electrodes 10 to 12 are made of anappropriate metal or alloy. Preferably, the first and second connectionelectrodes 10 to 12 and the heat diffusion layer 9 are plated layersformed by plating. That is, the first and second connection electrodes10 to 12, and the heat diffusion layer 9, which is made of metal, can beeasily provided by forming a plating film in through holes provided inthe piezoelectric substrate 2 and on the second main surface 2 b of thepiezoelectric substrate 2. In this case, it is preferable for the signalterminals 7 a to 7 c and the ground terminals 8 a to 8 e to be formed bya plating film formed in the same step.

However, the first and second connection electrodes 10 to 12, the heatdiffusion layer 9, the signal terminals 7 a to 7 c, and the groundterminals 8 a to 8 e may be formed using other methods.

The above-described IDT electrode 3, first electrode land 5 a, andsecond electrode lands 6 a and 6 b are made of an appropriate metal oralloy.

A supporting layer 13 is provided on the first main surface 2 a of thepiezoelectric substrate 2. The supporting layer 13 is preferably made ofsynthetic resin, for example. However, the supporting layer 13 may bemade of an insulating material, such as an inorganic insulator, forexample. Alternatively, the supporting layer 13 may be made of metal. Inthat case, the first electrode 5 a, which is connected to the signalpotential, the IDT electrode 3, and the IDT electrode 4 are notelectrically connected to the supporting layer 13. By connecting thesupporting layer 13 to the second electrode land 6 a connected to theground potential or to an additionally provided electrode land connectedto the ground potential, attenuation characteristics are furtherimproved.

A covering member 14 is stacked so as to cover a cavity provided by thesupporting layer 13. Accordingly, the supporting layer 13, the coveringmember 14, and the first main surface 2 a of the piezoelectric substrate2 define a hollow portion 15 in which the IDT electrodes 3 and 4 arelocated.

FIGS. 2 and 3 illustrate the signal terminals 7 a to 7 c, the groundterminals 8 a to 8 e, and the heat diffusion layer 9, which is made ofmetal, which are positioned on the second main surface 2 b. The signalterminal 7 a is a transmission terminal, and the signal terminal 7 b isa reception terminal. The signal terminal 7 c is a terminal connected toan antenna.

The signal terminal 7 c connected to the antenna is located on one oftwo sides of the heat diffusion layer 9, and the signal terminals 7 aand 7 b are located on the other side of the heat diffusion layer 9.That is, the heat diffusion layer is located between the signalterminals 7 a and 7 b, and the signal terminal 7 c. In doing so,interference between the signal terminal 7 c connected to the antennaand the signal terminals 7 a and 7 b is able to be reduced or prevented.In addition, the ground terminals 8 b and 8 c are located between thesignal terminal 7 a and the signal terminal 7 b. As such, isolationbetween the signal terminal 7 a defining and functioning as atransmission terminal and the signal terminal 7 b defining andfunctioning as a reception terminal is improved.

Furthermore, in the elastic wave filter apparatus 1, the heat diffusionlayer 9 is electrically connected to the IDT electrodes 3 and 4 with thesecond connection electrode 12 interposed therebetween. In the elasticwave filter apparatus 1, heat is generated by exciting the IDTelectrodes 3 and 4. This heat is rapidly transmitted to the heatdiffusion layer 9 through the electrode land 6 b and second connectionelectrode 12.

In addition, the heat diffusion layer 9 is at a position that overlapsat least a portion of the IDT electrodes 3 and 4 across thepiezoelectric substrate 2. Therefore, heat from the IDT electrodes 3 and4 is diffused through the piezoelectric substrate 2 to the heatdiffusion layer 9. This also effectively improves the heat dissipation.In particular, because the thermal conductivity of the heat diffusionlayer 9 is higher than the piezoelectric substrate 2, the heatdissipation is effectively increased by providing the heat diffusionlayer 9 in an area that overlaps at least a portion of the IDTelectrodes 3 and 4.

The area of the heat diffusion layer 9 is greater than that of each ofthe signal terminals 7 a to 7 c. As such, the heat dissipation isfurther effectively increased.

A mounting substrate 16 illustrated in FIG. 1 is preferably made ofinsulating ceramics or synthetic resin, for example. The mountingsubstrate 16 includes a first main surface 16 a and a second mainsurface 16 b, which face each other. A third electrode land 17 a, afourth electrode land 18 a, and a fifth electrode land 19 are providedon the first main surface 16 a. The third electrode land 17 a and thefourth electrode land 18 a are respectively bonded to the signalterminal 7 a and the ground terminal 8 a with metal bumps 20 a and 21 ainterposed therebetween. The fifth electrode land 19 is electricallyconnected to the heat diffusion layer 9 with a bonding material 22interposed therebetween. The third electrode land 17 a, the fourthelectrode land 18 a, and the fifth electrode land 19 are preferably madeof appropriate metal or alloy. In contrast, the bonding material 22 ispreferably made of metal or alloy, similar to the metal bumps 20 a and21 a, in the present preferred embodiment. Therefore, heat is rapidlydiffused from the heat diffusion layer 9 through the bonding material 20toward the fifth electrode land 19 side.

However, it is not necessary for the bonding material 22 to beelectrically conductive. It is only necessary for the bonding material22 to be made of a bonding material with higher thermal conductivitythan that of the piezoelectric substrate.

Preferably, the bonding material 22 is made of the same material as thatof the metal bumps 20 a and 21 a. In that case, the bonding material 22is able to be bonded in the same step.

When the elastic wave filter apparatus 1 is mounted on the mountingsubstrate 16 from the second main surface 2 b side of the piezoelectricsubstrate 2, heat dissipation is effectively increased. That is, becauseat least a portion of the IDT electrodes 3 and 4 overlaps the heatdiffusion layer 9 across the piezoelectric substrate, and the bondingmaterial 22 is located between the heat diffusion layer 9 and themounting substrate 16, heat dissipation is effectively increased.

In an elastic wave filter apparatus of the related art, air and sealingresin are present between a piezoelectric substrate and a mountingsubstrate, resulting in low heat dissipation.

In the present preferred embodiment, heat dissipation is effectivelyincreased due to the heat diffusion layer 9 and the bonding material 22.Therefore, even when a sealing resin layer is added so as to surroundthe structure illustrated in FIG. 1 , heat dissipation is sufficientlyincreased.

Additionally, attenuation characteristics of the elastic wave filterapparatus are unlikely to deteriorate. This will be described withreference to FIGS. 4 to 6 .

As an example of the elastic wave filter apparatus according to thefirst preferred embodiment, the frequency response of a Band 27 duplexeris obtained as below. Note that the Band 27 duplexer has a transmissionband of 807 MHz to 824 MHz and a reception band of 852 MHz to 869 MHz.

A LiTaO₃ substrate is used as the piezoelectric substrate 2. Asupporting layer is made of polyimide. A covering member is made ofpolyimide.

The duplexer includes the piezoelectric substrate 2, the supportinglayer 13, and a hollow portion surrounded by the covering member.

The IDT electrodes 3 and 4 are made of Al alloy. The signal terminals 7a to 7 c, the ground terminals 8 a to 8 e, and the heat diffusion layer9 are made of Cu, and preferably have a thickness of about 10 μm, forexample.

Note that a transmission filter including the IDT electrode 3 is aladder filter, and a reception filter including the IDT electrode 4 is alongitudinally coupled resonator-type bandpass filter.

Excluding the fact that no heat diffusion layer 9 is provided, aduplexer according to a comparative example is obtained similarly to theabove-described example.

FIG. 4 illustrates the attenuation amount frequency characteristics ofthe transmission filter of each of the duplexers according to theexample and the comparative example. FIG. 5 illustrates the attenuationamount frequency characteristics of the reception filter of each of theduplexers according to the example and the comparative example.

FIG. 6 illustrates the isolation characteristics of the example and thecomparative example. In FIGS. 4 to 6 , solid lines represent the resultsof the example, and broken lines represent the results of thecomparative example.

As is clear from FIG. 4 , comparing the example with the comparativeexample, the attenuation amount in the reception band is sufficientlyincreased in the attenuation amount frequency characteristics of thetransmission filter. In addition, the attenuation amount is sufficientlyincreased in a frequency range greater than or equal to about 890 MHz,which is higher than the reception band. Therefore, the out-of-bandattenuation amount of the transmission filter is unlikely todeteriorate.

Further, as is clear from FIG. 5 , comparing the example with thecomparative example, the attenuation amount in the transmission band,and the attenuation amount in a frequency range less than or equal toabout 790 MHz, which is lower than the transmission band, aresufficiently increased in the attenuation amount frequencycharacteristics of the reception filter. In addition, the attenuationamount is sufficiently increased in a frequency range greater than orequal to about 910 MHz. It is thus clear that the attenuationcharacteristics of the reception filter are unlikely to deteriorate inthe example.

Furthermore, as is clear from FIG. 6 , the isolation level is increasedin the reception band, in a frequency range less than or equal to about790 MHz, and in a frequency range greater than or equal to about 900 MHzin the isolation characteristics between the transmission filter and thereception filter.

As described above, the out-of-band attenuation characteristics of theduplexer are unlikely to deteriorate. Providing the heat diffusion layer9 may reduce or prevent the electrical interference between theelectrodes of the signal terminals 7 a to 7 c in addition to causing theincrease in heat dissipation as previously described.

FIG. 7 is a bottom view of an elastic wave filter apparatus according toa second preferred embodiment of the present invention. Although theground terminals 8 a to 8 e are independent in FIG. 3 , the groundterminals 8 a to 8 e may preferably be connected to the heat diffusionlayer 9 connected to the ground potential, as in the second preferredembodiment illustrated in FIG. 7 . Also in this case, the isolation isprovided between the signal terminal 7 a and the signal terminal 7 b,between the signal terminal 7 b and the signal terminal 7 c, and betweenthe signal terminal 7 a and the signal terminal 7 c by the heatdiffusion layer 9 and the ground terminals 8 b and 8 c connected to theheat diffusion layer 9.

FIG. 8 is a bottom view of an elastic wave filter apparatus 31 accordingto a third preferred embodiment of the present invention. Here,protruding portions 9 a to 9 c connected to the heat diffusion layer 9are preferably provided to extend between the signal terminal 7 a andthe ground terminal 8 b, between the ground terminal 8 b and the groundterminal 8 c, and between the ground terminal 8 c and the signalterminal 7 b. In addition, a protruding portion 9 d is provided betweenthe ground terminal 8 a and the signal terminal 7 c. The protrudingportion 9 d is connected to the heat diffusion layer 9.

The elastic wave filter apparatus 31 is preferably configured in thesame or similar manner as the elastic wave filter apparatus 1 except forthe above points.

Because the heat diffusion layer 9 and the protruding portions 9 a to 9d are provided in the elastic wave filter apparatus 31, heat dissipationis increased, and out-of-band attenuation characteristics is preventedfrom deteriorating. In particular, the heat diffusion layer 9 includesthe protruding portions 9 a to 9 d, and therefore, the area of thediffusion layer 9 is increased. As such, heat dissipation is moreeffectively increased.

FIG. 9 is a graph illustrating a heat simulation result in the case ofchanging the thickness of the piezoelectric substrate 2 to about 50 μm,about 80 μm, or about 125 μm in the elastic wave filter apparatus 31according to the third preferred embodiment, and the case of applyingelectric power to the IDT electrode 3 (a plurality of IDTs defining thetransmission filter). In FIG. 9 , the temperature of an IDT at thehighest temperature is extracted.

In FIG. 9 , white squares represent the results of the third preferredembodiment of the present invention, and black diamonds represent theresults of a second comparative example. The second comparative exampleis the same or substantially the same as the third preferred embodimentexcept for the point that the heat diffusion layer 9 and the protrudingportions 9 a to 9 d are not provided. As is clear from FIG. 9 ,comparing the third preferred embodiment to the second comparativeexample, heat dissipation is effectively increased. In particular, it isclear that heat dissipation is sufficiently increased even when thethickness of the piezoelectric substrate is increased.

FIG. 10 is a front cross-sectional view according to a fourth preferredembodiment of the present invention. In an elastic wave filter apparatus41, the first and second electrode lands 5 b and 6 a are extended toedges defined by lateral surfaces 2 c and 2 d and the first main surface2 a of the piezoelectric substrate 2. The first and second connectionelectrodes 10 a and 11 a are provided on the lateral surfaces 2 c and 2d. On the second main surface 2 b, the signal terminal 7 a and theground terminal 8 a are provided to extend to an edge defined by thelateral surface 2 c or the lateral surface 2 d and the second mainsurface 2 b. As such, the first electrode land 5 b and the signalterminal 7 a are electrically connected by the first connectionelectrode 10 a. Similarly, the second electrode land 6 a and the groundterminal 8 a are electrically connected by the second connectionelectrode 11 a. In this manner, as with the first and second connectionelectrodes 10 a and 11 a, connection electrodes provided on lateralsurfaces of the piezoelectric substrate may preferably be used.

Since the remaining configuration of the elastic wave filter apparatus41 is the same or substantially the same as the elastic wave filterapparatus 1, descriptions of the same portions are omitted and the samereference numerals are provided for the same or similar elements andportions.

FIG. 11 is a bottom view of an elastic wave filter apparatus accordingto a fifth preferred embodiment of the present invention. In an elasticwave filter apparatus 51, the ground terminal 8 b and the groundterminal 8 c are preferably integrated, as indicated by a broken line,on the second main surface 2 b of the piezoelectric substrate 2.Similarly, the ground terminal 8 d and the ground terminal 8 e arepreferably integrated, as indicated by a broken line. The groundterminals 8 a to 8 e are all connected to the heat diffusion layer 9. Inthis manner, all of the ground terminals 8 a to 8 e may be electricallyconnected to the heat diffusion layer 9.

The elastic wave filter apparatus 51 is the same or substantially thesame as the elastic wave filter apparatus 1 according to the firstpreferred embodiment except for the above-described points.

In an elastic wave filter apparatus 61 according to a sixth preferredembodiment of the present invention illustrated in FIG. 12 , the heatdiffusion layer 9 is preferably divided into a plurality of heatdiffusion layers 9 e and 9 f. In this manner, the heat diffusion layer 9may be divided into the plurality of heat diffusion layers 9 e and 9 f.Also in this case, the heat diffusion layer 9 e or the heat diffusionlayer 9 f is positioned between the signal terminal 7 a and the signalterminal 7 c and between the signal terminal 7 b and the signal terminal7 c. Therefore, the same or similar advantageous effects as those of thefirst preferred embodiment are achieved.

FIG. 13 is a bottom view of an elastic wave filter apparatus 71according to a seventh preferred embodiment of the present invention. Asin the elastic wave filter apparatus 71, the heat diffusion layer 9 maypreferably be provided on the second main surface 2 b of thepiezoelectric substrate 2 so as to extend from one edge to another edge.Here, frames 9 g and 9 h extending from one end to another end of theheat diffusion layer 9 and surrounding the outer peripheral of thesecond main surface 2 b are provided to be continuous with the heatdiffusion layer 9. The frames 9 g and 9 h are connected to the heatdiffusion layer 9.

In an elastic wave filter apparatus 81 according to an eighth preferredembodiment of the present invention illustrated in FIG. 14 , loops 9 ito 9 k that are continuous with the heat diffusion layer 9 and thatsurround the signal terminals 7 a, 7 b, and 7 c, respectively, arepreferably provided. In this manner, when the loops 9 i to 9 k,connected to the ground potential, surround the signal terminals 7 a to7 c, respectively, out-of-band attenuation characteristics iseffectively prevented from deteriorating.

FIG. 15 is a front cross-sectional view of an elastic wave filterapparatus 91 according to a ninth preferred embodiment of the presentinvention. In the elastic wave filter apparatus 91, a resin layer 92 ispreferably provided on the second main surface 2 b of the piezoelectricsubstrate 2. The first and second connection electrodes 10 to 12penetrate the resin layer 92. The signal terminal 7 a and the groundterminal 8 a are provided on the resin layer 92. The resin layer 92 maypreferably be provided in the elastic wave filter apparatus 91. In doingso, moisture resistance is increased.

FIG. 16 is a bottom view of an elastic wave filter apparatus 101according to a tenth preferred embodiment of the present invention. Inthe elastic wave filter apparatus 101, the signal terminals 7 a to 7 cand the ground terminals 8 a to 8 e are preferably provided on thesecond main surface 2 b so as to be provided along with an edge 2 c 1 oran edge 2 d 1 defined by a lateral surface and the second main surface 2b of the piezoelectric substrate 2. In the elastic wave filter apparatus101, the signal terminals 7 a to 7 c and the ground terminals 8 a to 8 epreferably have a rectangular or substantially rectangular planar shape,for example.

Similarly, in an elastic wave filter apparatus 111 according to aneleventh preferred embodiment of the present invention illustrated inFIG. 17 , the signal terminals 7 a to 7 c and the ground terminals 8 ato 8 e are preferably provided along the edge 2 c 1 or the edge 2 d 1.In the elastic wave filter apparatus 111, the signal terminals 7 a to 7c and the ground terminals 8 a to 8 e preferably have a semicircular orsubstantially semicircular planar shape, for example. As describedabove, the planar shape and location of each signal terminal and groundterminal are not particularly limited.

As in the above-described elastic wave filter apparatuses 101 and 111,when the signal terminals 7 a to 7 c and the ground terminals 8 a to 8 eare provided along the edge 2 c 1 or the edge 2 d 1, connectionelectrodes provided on the lateral surface 2 c or the lateral surface 2d are able to be suitably used as the first and second connectionelectrodes.

FIG. 18 is a front cross-sectional view of an elastic wave filterapparatus according to a twelfth preferred embodiment of the presentinvention. In an elastic wave filter apparatus 121, a concave portion 2x is preferably provided on the second main surface 2 b of thepiezoelectric substrate 2. The second main surface 2 b includes a bottomsurface of the concave portion 2 x, side walls 2 e, and frame portions 2f.

The signal terminal 7 a and the ground terminal 8 a are provided on thebottom surface of the concave portion 2 x of the second main surface 2b. Here, a heat diffusion layer 9A is preferably provided to becontinuous with the ground terminal 8 a. The metal bump 20 a is providedon the signal terminal 7 a, and the metal bump 21 a is provided on theground terminal 8 a. The metal bumps 20 a and 21 a protrude to theoutside beyond the concave portion 2 x. Therefore, the elastic wavefilter apparatus 121 is able to be bonded to the electrode lands on themounting substrate using the metal bumps 20 a and 21 a.

In the elastic wave filter apparatus 121, the heat diffusion layer 9A ispreferably positioned in a portion that overlaps the IDT electrode 3across the piezoelectric substrate 2. The thickness of the piezoelectricsubstrate 2 is thinner by an amount corresponding to the concave portion2 x, in the portion where the heat diffusion layer 9A is provided.Therefore, heat generated at the IDT electrode 3 is not only dissipatedthrough the second electrode land 6 a and the second connectionelectrode 11, but also is able to be rapidly dissipated through theinterior of the piezoelectric substrate 2 to the heat diffusion layer 9Afacing the IDT electrode 3 across the piezoelectric substrate 2.Therefore, heat dissipation is effectively increased.

In the elastic wave filter apparatus 121, because the thickness of thepiezoelectric substrate 2 is reduced by providing the concave portion 2x, it becomes easier to form via holes for the first connectionelectrode 10 and the second connection electrode 11.

Although not illustrated in FIG. 18 , a third electrode landelectrically connected to the IDT electrode 3 may preferably beelectrically connected to the heat diffusion layer 9A in anunillustrated portion.

The concave portion 2 x may be filled with synthetic resin to eliminatean elevation difference with the frame portions 2 f of the piezoelectricsubstrate 2.

FIG. 19 is a front cross-sectional view of an elastic wave filterapparatus according to a thirteenth preferred embodiment of the presentinvention. In an elastic wave filter apparatus 131, the secondconnection electrode 12 illustrated in FIG. 2 is preferably notprovided. Also, the second electrode land 6 b illustrated in FIG. 2 ispreferably not provided. Instead, an IDT electrode 132 is provided at aposition at which the second electrode land 6 b is provided. In thepresent preferred embodiment, the heat diffusion layer 9 is notconnected to the second electrode land. Also in this case, because theheat diffusion layer 9 faces the IDT electrode 132 across thepiezoelectric substrate 2, heat generated at the IDT electrodes 3, 4,and 132 propagates through the piezoelectric substrate 2 and is rapidlytransmitted to the heat diffusion layer 9. The other structure of theelastic wave filter apparatus 131 is preferably the same orsubstantially the same as the elastic wave filter apparatus 1.

Also in the elastic wave filter apparatus 131, the heat diffusion layer9 is provided on the second main surface 2 b of the piezoelectricsubstrate 2. The heat diffusion layer 9 is bonded to the third electrodeland 19 illustrated in FIG. 1 with the bonding material 22 interposedtherebetween when the elastic wave filter apparatus 131 is mounted onthe mounting substrate 16 illustrated in FIG. 1 . Therefore, similarlyto the elastic wave filter apparatus 1, the heat diffusion layer 9 iselectrically connected to the third electrode land 19 connected to theground potential. Therefore, electrical coupling between the signalterminal 7 a and the ground terminal 8 a is effectively reduced orprevented. In doing so, attenuation characteristics are improved.Additionally, because the heat diffusion layer 9 is provided, heatgenerated at the IDT electrodes 3, 4, and 132 is rapidly transmittedthrough the piezoelectric substrate 2 to the heat diffusion layer 9.Therefore, heat diffusion is also increased.

Because the second electrode land 6 b is unnecessary in the elastic wavefilter apparatus 131, an area in which the IDT electrodes are located isable to be increased. This increases the degree of design freedom.

FIG. 20 is a partially-notched front cross-sectional view illustrating aportion where an elastic wave filter apparatus 141 according to afourteenth preferred embodiment of the present invention is mounted on amounting substrate. In the elastic wave filter apparatus 141, a devicesubstrate 142 includes a supporting substrate 143 and a piezoelectriclayer 144 provided on the supporting substrate 143. The piezoelectriclayer 144 is positioned on a first main surface side of the devicesubstrate 142. The piezoelectric layer 144 is preferably made ofpiezoelectric single crystal, such as LiTaO₃ or LiNbO₃, or piezoelectricceramics, for example. The supporting substrate 143 is preferably madeof Si in the present preferred embodiment. However, the material usedfor the supporting substrate 143 is not limited to Si. As such amaterial, an appropriate material through which a bulk wave propagatesat a higher acoustic velocity than an elastic wave that propagatesthrough the piezoelectric layer 144, or a material whose thermalconductivity is higher than that of the piezoelectric layer 144 ispreferably used. Such a material includes sapphire, in addition to Si.

Since the remaining configuration of the elastic wave filter apparatus141 is the same or substantially the same as the elastic wave filterapparatus 1, descriptions of the same portions are omitted the samereference numerals are provided for the same or similar elements andportions.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. An elastic wave filter apparatus comprising: adevice substrate including a piezoelectric layer, the device substrateincluding a first main surface and a second main surface that face eachother; at least two excitation electrodes provided on the first mainsurface of the device substrate, the at least two excitation electrodesdefining an elastic wave filter device; a first electrode land providedon the first main surface of the device substrate and connected to oneof the at least two excitation electrodes, the first electrode landbeing connected to a signal potential; a plurality of second electrodelands provided on the first main surface of the device substrate, theplurality of second electrode lands being electrically connected to aground potential, at least one of the plurality of second electrodelands electrically connected to the at least two excitation electrodes,and the at least one of the plurality of second electrode lands isprovided in an area between the at least two excitation electrodes; asignal terminal and a plurality of metal members provided on the secondmain surface of the device substrate, the signal terminal beingconnected to the signal potential, the plurality of metal members beingconnected to the ground potential; a first connection electrode thatconnects the first electrode land and the signal terminal; a secondconnection electrode that electrically connects the at least one of theplurality of second electrode lands and at least one of the plurality ofmetal members; wherein the at least one of the plurality of metalmembers is electrically connected to the at least two excitationelectrodes through the second connection electrode and the at least oneof the plurality of second electrode lands, and the at least one of theplurality of metal members overlaps at least a portion of each of the atleast two excitation electrodes across the device substrate.
 2. Theelastic wave filter apparatus according to claim 1, further comprising:a supporting layer provided on the first main surface of the devicesubstrate; a cover provided on the supporting layer; wherein thesupporting layer, the cover, and the first main surface of the devicesubstrate define a hollow portion in which the at least two excitationelectrodes are located.
 3. The elastic wave filter apparatus accordingto claim 1, wherein at least one of the plurality of metal members is aground terminal.
 4. The elastic wave filter apparatus according to claim1, wherein an area of at least one of the plurality of metal members isgreater than an area of the signal terminal.
 5. The elastic wave filterapparatus according to claim 1, wherein the first and second connectionelectrodes penetrate through the device substrate.
 6. The elastic wavefilter apparatus according to claim 1, wherein the device substrateincludes a lateral surface connecting the first main surface and thesecond main surface, and the first and second connection electrodes areprovided on the lateral surface.
 7. The elastic wave filter apparatusaccording to claim 1, wherein the first and second connection electrodesand at least one of the plurality of metal members include a platingfilm.
 8. The elastic wave filter apparatus according to claim 1, whereinthe signal terminal includes a plurality of signal terminals provided onthe second main surface of the device substrate, at least one of theplurality of signal terminals is located on one of two sides of the atleast one of the plurality of metal members connected to the secondconnection electrode, and at least another one of the plurality ofsignal terminals is located on the other side of the at least one of theplurality of metal members connected to the second connection electrode.9. The elastic wave filter apparatus according to claim 8, wherein theplurality of signal terminals have a rectangular or substantiallyrectangular planar shape.
 10. The elastic wave filter apparatusaccording to claim 8, wherein the plurality of signal terminals have asemicircular or substantially semicircular planar shape.
 11. The elasticwave filter apparatus according to claim 8, wherein each of theplurality of signal terminals extends along one of opposed edges of thedevice substrate.
 12. The elastic wave filter apparatus according toclaim 1, wherein the device substrate is a piezoelectric substrateincluding the piezoelectric layer.
 13. The elastic wave filter apparatusaccording to claim 1, wherein the device substrate includes a supportingsubstrate and the piezoelectric layer is provided on the supportingsubstrate.
 14. The elastic wave filter apparatus according to claim 1,wherein at least one of the plurality of metal members is located on oneof two sides of the at least one of the plurality of metal membersconnected to the second connection electrode, and at least another oneof the plurality of metal members is located on the other side of the atleast one of the plurality of metal members connected to the secondconnection electrode.
 15. The elastic wave filter apparatus according toclaim 14, wherein the plurality of metal members have a rectangular orsubstantially rectangular planar shape.
 16. The elastic wave filterapparatus according to claim 14, wherein the plurality of metal membershave a semicircular or substantially semicircular planar shape.
 17. Theelastic wave filter apparatus according to claim 14, wherein each of theplurality of metal members extends along one of opposed edges of thedevice substrate.